[ RadSafe ] Testing bombs

Steven Dapra sjd at swcp.com
Mon Jun 30 19:25:30 CDT 2008

June 30


         Thank you for explaining these technical distinctions.  Although 
we probably don't need to use them in everday discourse we still need to 
know them and have that knowledge stored away in the back of our minds 
should it become necessary to use it.

Steven Dapra

At 03:01 PM 6/30/08 -0500, Geo>K0FF wrote:
>Hi Jim, my semantics are correct, if not popular. Whoever said "being 
>popular doesn't make it right"?
>I cite Cosmic Rays (not rays at all), Pencil LEAD ( not lead at all), but 
>the masses like things simple.
>Since this is a technical discussion group, perhaps we should refrain from 
>the popular jargon and speak technically.
>Just an opinion.
>The distinction you make concerning the energy in a nuclear bomb coming 
>from binding energy is quite correct. In  a nuclear bomb, the E=MC>2 
>matter to energy conversion has to do with the energy deficit (also 
>related to binding energy) when an atomic nucleus is formed. The sum
>weight of the protons and neutrons in a nucleus is less than the intrinsic 
>weight of the protons and neutron individually. It is this mass
>difference, not the mass of the protons or neutrons that enter into the 
>release of energy by conversion of matter to energy.
>Protons can convert to neutrons, and neutrons can become protons in normal 
>nuclear reactions, but they always remain.
>Photons can turn into matter in the "pair production" reaction, and matter 
>can turn into photons in the positron annihilation reaction.
>George Dowell
>New London Nucleonics Lab
>GEOelectronics at netscape.com
>----- Original Message ----- From: "Dukelow, James S Jr" <jim.dukelow at pnl.gov>
>To: "Steven Dapra" <sjd at swcp.com>; <radsafe at radlab.nl>
>Sent: Monday, June 30, 2008 12:52 PM
>Subject: RE: [ RadSafe ] Testing bombs
>Nobody has really answered Dapra's original question, which has some 
>contemporary relevance.
>The difference between the U-235 bomb and the Pu-239 bomb is that the 
>Pu-239 was contaminated with other isotopes of Pu that have significant 
>spontaneous fission rates.  If the process of assembling a critical mass 
>was "slow" (say, tens of milliseconds), there would be a significant 
>probability that the assembling critical mass would be "pre-ignited" by 
>stray neutrons from the spontaneous fissions, leading to a lower yield -- 
>a "fizzle".  The answer was to used carefully designed explosive charges 
>to assemble the critical mass very quickly.  Until Trinity, the implosion 
>design was theoretical and the test was need to give confidence that the 
>weapon would work.
>All of this is very nicely described in The Los Alamos Primer, by Robert 
>Serber.  It is the annotated notes of the lectures that Serber gave to 
>physicists and other arriving at Los Alamos to participate in the 
>Manhattan Project.  The notes were published in 1992 and are currently 
>available from Amazon.
>This problem did not exist with U-235 and the physicists were quite 
>confident it would work the first time.
>The current relevance is that Iran, and earlier, North Korea is/were using 
>both plutonium production and uranium enrichment to pursue nuclear weapon 
>capability.  The weaponization issues remain with plutonium weapons and 
>uranium weapons remain simple to implement once sufficient fissile 
>material is available (although "deliverable" weapons may be more of an issue).
>Dowell's linguistic distinction between nuclear (fission and fusion) 
>explosions and atomic/chemical explosions is not standard usage, but is 
>reasonable.  The nuclear weapons involve the release of the nuclear 
>binding energy of the atomic nucleus, while chemical explosions release 
>the chemical binding energy of the electron orbitals.
>Hanford's weapons mission is over and it is probably not to hard to 
>arrange tours of most of the facilities, although I haven't tried to do it.
>Best regards.
>Jim Dukelow
>Pacific Northwest National Laboratory
>Richland, WA
>jim.dukelow at pnl.gov
>These comments are mine and have not been reviewed and/or approved by my 
>management or by the U.S. Department of Energy.
>-----Original Message-----
>From: radsafe-bounces at radlab.nl on behalf of Steven Dapra
>Sent: Sat 6/28/2008 8:49 AM
>To: radsafe at radlab.nl
>Subject: [ RadSafe ] Testing bombs
>June 28, 2008
> From time to time I have read that one of the Hiroshima and Nagasaki bombs
>had to be tested before it was used, and that one did not --- that the
>engineers were so certain the latter bomb would explode that they didn't
>bother testing it.  I also read recently that hydrogen bombs must be
>tested.  Of these three types of bombs, which ones must be tested, and
>why?  For the one that did not have to be tested, why not?  (I don't have
>any bombs I want to test, I am merely curious.)
>Steven Dapra
>sjd at swcp.com

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